The internal trackpad on my mac is basically dead/unusable. I have a trackpad app on my tablet, and a server app on the computer that talks to the tablet app to provide an effective trackpad.

If I am in a gui – anytime that the normal OS mouse pointer would show – then the virtual trackpad words fine.

I can two-finger scroll to change the selected item, no problem.

But I can no longer aim left/right. This was working about a month or two ago.

I can confirm that this behavior exists in 1.11.2.
I do not know if it ever worked correctly in 1.11.2.
It did "used to work" in 1.10.2, and does not anymore.

EDIT: In case this is a Lwjgl issue, see also: http://forum.lwjgl.org/index.php?topic=6477.0